which are
objects altogether incompatible. It is impossible by one steady view to
survey the opposite chances, and the events dependent on them; but it is
necessary, that the imagination should run alternately from the one to
the other. Each view of the imagination produces its peculiar passion,
which decays away by degrees, and is followed by a sensible vibration
after the stroke. The incompatibility of the views keeps the passions
from shocking in a direct line, if that expression may be allowed; and
yet their relation is sufficient to mingle their fainter emotions. It is
after this manner that hope and fear arise from the different mixture of
these opposite passions of grief and joy, and from their imperfect union
and conjunction.

Upon the whole, contrary passions succeed each other alternately, when
they arise from different objects: They mutually destroy each other,
when they proceed from different parts of the same: And they subsist
both of them and mingle together, when they are derived from the
contrary and incompatible chances or possibilities, on which any one
object depends. The influence of the relations of ideas is plainly seen
in this whole affair. If the objects of the contrary passions be totally
different, the passions are like two opposite liquors in different
bottles, which have no influence on each other. If the objects be
intimately connected, the passions are like an alcali and an acid,
which, being mingled, destroy each other. If the relation be more
imperfect, and consists in the contradictory views of the same object,
the passions are like oil and vinegar, which, however mingled, never
perfectly unite and incorporate.

As the hypothesis concerning hope and fear carries its own evidence
along with it, we shall be the more concise in our proofs. A few strong
arguments are better than many weak ones.

The passions of fear and hope may arise when the chances are equal on
both sides, and no superiority can be discovered in the one above the
other. Nay, in this situation the passions are rather the strongest, as
the mind has then the least foundation to rest upon, and is tossed with
the greatest uncertainty. Throw in a superior degree of probability to
the side of grief, you immediately see that passion diffuse itself over
the composition, and tincture it into fear. Encrease the probability,
and by that means the grief, the fear prevails still more and more, till
at last it runs insensibly, as th